For a case I recommend Garmin's low-cost black nylon 010-10117-02 case - nothing fancy, but it works well. Consider getting a screen protector from http:www.zagg.com . If you think you might use it in a car consider getting a 12V automotive power cord.

For pre-defining and loading waypoints and storing waypoints and routes created in the field I use software from http://www.geobuddy.com . The software provides on-line topo for the U.S. and satellite pics for most of the U.S. It makes defining and pre-loading waypoints real simple. Its from Topografix.com - the same folks who make EasyGPS (free, but no on-line maps) and ExpertGPS.

Oh, and you'll need maps. Topo for outdoors and City Navigator for the road. I got the City Navigator pre-loaded on a microSD memory card and really like it. I keep them in a little pouch in the GPS case and swap them out as needed with no software downloading. Others prefer the software version.

To be honest, I actually use my GPS in my truck more than in the field. Its actually that good an automotive GPS. The auto-routing is awesome!

Consider buying a used copy of "GPS Land Navigation". Its available from Amazon.com for about $5. Its section on selecting a GPS is so old its like walking through a museum, but its still the best "how to use a GPS with a map and compass" book I've seen.

Here are some great tips on GPS use from the U.S. Geological Survey: http://rockyweb.cr.usgs.gov/outreach/gps/compass_gps_north.html

If you don't know about UTM coordinates, check out http://www.maptools.com .

This short "how to" from REI isn't bad: http://www.rei.com/expertadvice/articles/gps+receiver+howto.html BUT don't use lithium batteries in the 60 series GPS.

... and last but not least, here is a poorly publicized user guide by Garmin called "Using a Garmin GPS with Paper Land Maps":

http://www8.garmin.com/manuals/UsingaGarminGPSwithPaperLandMaps_Manual.pdf

Enjoy!!